Schizophrenia:
Schizophrenia is a debilitating mental disorder characterized primarily by psychotic symptoms including hallucinations, delusions, disorganized speech, thought and behaviour, and difficulty expressing emotion. The lifetime prevalence of schizophrenia is about 1% of the population worldwide, with some countries slightly lower and others slightly higher. In the United States, roughly 2,500,000 people are affected by it.
Diagnosis of Schizophrenia
Currently diagnosis of schizophrenia relies solely on the analysis of a person's symptoms. Diagnosis is made from information obtained from physicial examination, taking a person's family history and emotional history, as well as a medical evaluation, and a mental status examination. Relying on symptomatic history makes diagnosis of schizophrenia difficult, particularly since no single symptom is definitive for diagnosis. Rather, the diagnosis encompasses a pattern of signs and symptoms, in conjunction with impaired occupational or social functioning. Currently diagnosis includes looking for delusions (false beliefs strongly held in spite of invalidating evidence); visual, auditory, tactile, olfactory or gustatory hallucinations; disorganized speech; disorganized thinking; grossly disorganized thinking and/or catatonic behaviour; negative symptoms, such as emotional deficit, avolition (inability to initiate and persist in goal-directed activities) and alogia (poverty of speech) are also symptoms of schizophrenia. Continuous signs of the disturbance must persist for at least 6 months. This 6-month period must include at least 1 month of active-phase symptoms (listed above) (or less if successfully treated) and may include periods of prodromal or residual symptoms. During these prodromal or residual periods, the signs of the disturbance may be manifested by only negative symptoms or two or more active-phase symptoms in an attenuated form (e.g., odd beliefs, unusual perceptual experiences).
Diagnosis of schizophrenia is made even harder because it is often difficult to differentiate schizophrenia from other mental disorders including bipolar disorder, schizoaffective disorder, and brief psychotic disorder. In addition, diagnosis of schizophrenia is often confused with other organic medical conditions (e.g. encephalitis) or substance conditions (drugs of abuse, such as amphetamines and phencyclidine, or other medications). Although recently brain imaging techniques have been utilized as a tool towards diagnosis, this is costly, is inconvenient to patients, and is not considered very reliable.
Bipolar Disorder:
Bipolar disorder, (also termed manic-depressive disorder), is a mood disorder in which people experience alternating episodes of mania and major depression. Mania is characterized by elation, irritability, excitability, racing thought and speech, and hyperactivity. Major depression is characterized by sadness, withdrawal, despair, and suicidal thoughts. Bipolar disorder affects approximately 3% of people in the United States. The age of onset is usually the late teens or early 20s and there is usually a history of depression. Generally, early treatment means better prognosis.
Diagnosis of Bipolar Disorder
Traditional medical diagnostic techniques for diagnosing bipolar disorder include: physical exam and history and mental status exam for presence of bipolar disorder symptoms which include a combination of at least one major depressive episode (a depressed mood or a loss of interest or pleasure in daily activities consistently for at least a 2 week period which represents a change from the person's normal mood; social, occupational, educational or other important functioning must also be negatively impaired by the change in mood) and one manic episode (a distinct period of persistently elevated, expansive, or irritable mood, lasting throughout at least 4 days, that is clearly different from the usual nondepressed mood). Diagnosis can be difficult because the first episode of mania may go undetected, and an episode of depression does not necessarily predict a subsequent manic episode. Most people are symptom free for months or even years between episodes of depression and mania. In brief, both schizophrenia and bipolar disorder are difficult to diagnose due to the complexity of each condition. Moreover, it can be challenging to clinically distinguish these two conditions because of their common clinical characteristics. It often requires a long period of observation of a patient before the definitive diagnosis can be made. Although there are brain-imaging tests available, they are not specific enough. Recently there has been some advancement in analyzing gene expression in brain tissue to identify biomarkers of mental disorders, but one cannot translate this into a simple non invasive diagnostic tool. Blood-based tests for diagnosis and differential diagnosis of schizophrenia and bipolar disorder would help speed up the diagnostic process and ensure an early administration of the correct therapy. This is particularly important since there are effective therapies available to manage both schizophrenia and bipolar disorder, and early treatment in many cases means better prognosis and decreases chances of recurrence of future acute episodes.
Thus there is a need for a simple non-invasive diagnostic test for diagnosing an individual as having either schizophrenia or bipolar disorder.